A JP Morgan trading gameplan outlines five potential market scenarios for the upcoming rate decision and their projected impacts on the S&P 500. A no-rate-hike decision is projected to cause the S&P 500 to fall 1.25% to 1.75%. Conversely, a 25 basis point hike with no guidance is expected to spur equities higher, pushing the S&P 500 up 0.25% to 0.75%.